The United Nations has made an urgent appeal for funds to help save millions of Pakistanis affected by monsoon floods and unrest in the country's north-west.

Pakistan has been suffering from a series of devastating floods over the past two years, including its worst ever on record in 2010, which called more than 1,800 people and affected 21 million.

This year monsoon floods in Pakistan have killed 480 people and affected more than five million, according to the government's disaster relief agency.

During a visit to the affected areas, the UN's assistant Secretary General for Humanitarian Affairs, Catherine Bragg, says Pakistan urgently needs $US79 million to meet immediate needs.

"Winter is coming, making the need even more urgent," she said.

"Hundreds of thousands are still in need of food and shelter - and over one million people are estimated to still be in need (of) health care, water and sanitation services and agricultural inputs."

The UN has estimated a total of $169 million dollars, and Ms Bragg says so far it has has received only $52 million in pledges.

"We look to donors for their generosity," she said.

Most of those hit by the latest floods were in southern Sindh province, where the National Disaster Management Authority (NDMA) said more than 3 million have been affected, with 887,345 in Punjab and nearly a million in Baluchistan province.

More than 159,023 people around the country have sought shelter in 108 relief camps since early September, though this figure is down from the 290,000 reported by NDMA earlier.

The data published by NDMA last week said more than 450,000 hectares of crops were affected by the floods.

In addition to those who have fled natural disasters, nearly half a million Pakistanis are estimated to have escaped fighting between soldiers and militia on the Afghan border this year and taken shelter at Jalozai camp, near the north-western city of Peshawar.

Suicide and bomb attacks blamed on Islamist insurgents have killed more than 5,200 people across Pakistan since July 2007.